1. Field of the Invention
The present invention relates to a paper discharging apparatus for sequentially discharging a sheet of paper having an image thereon onto a paper discharging base of a printer, etc. and a paper discharging tray of an on-line sorter for receiving and sorting a sheet of sheet discharged from the printer, etc. on line. The present invention also relates to a paper discharging apparatus used in a rotary stencil duplicator.
2. Description of the Related Art
As is well known, in a printer and an on-line sorter, a sheet of paper having a printed image thereon is sequentially discharged and stacked on a paper discharging base or tray by a paper-discharging conveying means within the printer.
The general printer and the general on-line sorter are constructed such that the paper-discharging conveying means approximately discharges the sheet of paper in a horizontal direction. Therefore, a front end of the paper sheet discharged by the paper-discharging conveying means hangs down by its empty weight.
Accordingly, in the printer or the on-line sorter mentioned above, the discharged paper sheet is moved in a paper discharging direction while the front end of the discharged paper sheet comes in frictional contact with a printed image face of the paper sheet previously discharged and stacked on the paper discharging base. Therefore, a printed image of the paper sheet previously discharged and stacked on the paper discharging base is damaged by this front end of the discharged paper sheet. Further, the front end of the discharged paper sheet is dirtied by this printed image.
To solve such problems, in a proposed paper discharging apparatus, the discharged paper sheet is curved in an arc shape in cross section in a direction perpendicular to the paper discharging direction. Thus, a bending strength of the paper sheet as an apparent rigidity in the paper discharging direction is increased to prevent the front end of the paper sheet from hanging down when the paper sheet is discharged.
For example, Japanese Patent Application Laying Open (KOKAI) No. 56-61266 shows a device for discharging and guiding a sheet of paper. In this device, a pair of guide members are disposed on opposite sides. A distance between the guide members is increased from a paper discharging port along a paper discharging direction. The guide members have edge portions inclined upwards. The guide members extend from the paper discharging port in the paper discharging direction. A sheet of paper passes through a space between these guide members such that the paper sheet is moved from a lower side to an upper side. Thus, the paper sheet is curved in an arc shape in cross section in a direction. Accordingly, an apparent rigidity of the paper sheet is increased in the paper discharging direction to prevent a front end of the paper sheet from hanging down when the paper sheet is discharged.
In this paper-discharging guiding device shown in Japanese Patent Application Laying Open (KOKAI) No. 56-61266, the pair of guide members extend from the paper discharging port in the paper discharging direction. Accordingly, a curving state of the paper sheet can be maintained for a long time. However, since the guide members extend to an upper portion of a paper discharging tray, it is not easy to take out paper sheets discharged and stacked on the paper discharging tray. Further, there is a fear that the discharged paper sheets and the guide members are damaged. Furthermore, when a paper sheet having a stronger bending strength is discharged, there is a case in which the paper sheet does not drop as expected and is caught by the guide members therebetween and is moved and stopped on the guide members, thereby tending to cause a discharged paper jam.
To solve the above problems, there is a method for increasing a difference in distance between the paper discharging port and a stacking face of the paper sheet in a paper discharging section. In this method, a paper discharging space of the paper discharging base is increased in a vertical direction such that no front end of the discharged paper sheet comes in contact with a surface of the paper sheet previously discharged and stacked on the paper discharging base. However, in this method, it is necessary to separately dispose a paper discharging space above the paper discharging base in addition to a space for stacking paper sheets. Accordingly, for example, when this method is applied to a paper discharging apparatus of an on-line sorter having many paper discharging trays, the entire apparatus is very large-sized since respective distances between the paper discharging trays are increased.
Further, an air layer flows out of the paper sheet at both side edges thereof as the paper sheet is moved forward in the paper feeding direction. Accordingly, an air pressure is reduced so that no upper and lower paper sheets can be separated from each other. As a result, problems similar to those in the general paper discharging apparatus are caused. Therefore, these problems cannot be effectively solved by the general paper discharging apparatus.